Biological basis of homosexuality

Is there a biological basis for homosexuality? This question has already been settled in the affirmative as far as possible in biological science. But here I dwell on novel and further authoritative approaches to settling the biological basis for homosexuality.

Why am I undertaking this task? Comrade Ekow Nelson commented extensively on homosexuality when condemning the decision to disallow a gay conference in Ghana last year. In the ensuing debates on the Ghanaian internet forum Okyeame, I promised to enlighten forumers on the biological basis of homosexuality. I underestimated the difficulty of writing for a forum of predominantly non biologists. I did not lose a night’s sleep when the debate moved on.

This week, an Akyeame reminded me of my promise and even threatened to keep reminding me until I honour my promise. Then another Akeame wrote in response to another thus: “I have never understood all this gay fuss, I really do not understand why people should be granted any special societal privileges simply by the way they chose to copulate. Or who they decide to have sex with. Does it mean I can organise and claim certain privileges if I decide to have sex with bats only. Educate me on this”

Colourful language that! nevertheless it energised me to attempt some education of sorts. I apologise to those I lose on my way to explaining why homosexuality is beyond the control of some homosexuals. I start with definitions - sex differentiation v sex identification.

Sex or gender differentiation or determination is the formation of gonads and internal and external genitalia in male (by 10 weeks of pregnancy) and female (by 12 weeks or end first trimester of pregnancy) fetuses. The process is guided by sex chromosomes, hormones, receptors and enzymes - absence or ineffectiveness of any of which results in abnormalities of sexual differentiation. And not just underdevelopment of sexual organs, but resulting sexual organs that mimic that of the opposite sex to varying degrees. Development of brain appropriate to sex or gender is now regarded as part of normal sexual differentiation.

Sex or gender identification is however the sex of a person’s identification. Gender identification has both subjective and objective components. The term Gender identity is the subjective self estimation of one’s gender. The term Gender role is reserved for the objective estimation of one’s gender, corresponding to a person’s sexual differentiation. A person’s gender/sexual orientation is usually coincidence of one’s gender identity and gender role i.e. subjective equals objective estimation of one’s gender. Collectively, gender identity, gender role and sexual orientation is referred to as Psychic sex.

From a strict biological point of view, a homosexual is a person whose gender identity is at variance with his gender role.

Evolution is opportunistic and at the same time conservative, above all it is purposeful - to maximise survival. Where the evolutionary end of a reproductive organ is procreation, there would be development of behavioural tendencies to put sexual organs to sexually functional effect. In the non hermaphroditic human, development of sex organs must therefore be associated with development of preference for the opposite sex as sexual partners, so as to give functional expression to developed sex organs. In humans, therefore, normal sexual development would require coincidence of genetic sex (sex chromosomes), gonadal sex (testes or ovaries), genitalia sex (external and internal sex organs), somatic sex (body characteristics, in particular pattern of fat deposition) and psychic sex.

By the definitions above, a homosexual whose gender identity is at variance with gender role does not necessarily have to prefer same sex as sexual partners. But even they do, it is not counter evolution, because evolution may well provide deliberate ambiguity in gender identity and gender role for purposes of population control that would preserve survival of the species as a whole.

I have been interested for a while in such evolutionary niceties in population control. Banana plantation workers in South America in days when pesticides were used carelessly had more girls than boys. The pesticides with estrogenic effects compromised fertility of the male workers. In wars, in famines, in migrations of male workers, surviving populations first increase female to male sex birth ratios as the first step to regaining populations. In Humans, a single man does not usually impregnate more than one woman at a time. Still, this sex ratio change in response to population threat remains. We could probably have sex reversals towards females if we were alligators, as was found in a Florida lake where the alligator population was threatened by environmental toxicants with estrogenic effects.

What is it that makes a genetic male think and sexually behave like a male? This question is the easiest to answer in elaborating on the biological basis of homosexuality. Estrogen is responsible for masculinising the brain. The Estrogen that masculinises male fetus brains is formed from testosterone of adrenal origin by a process called aromatisation. Incidentally it has also been found that Estrogen also defeminizes the brain. So why doesn’t Estrogen in females similarly masculinise the brain of the female fetus? Because the female has a protein called alpha feto-protein, AFP, that prevents estrogen from masculizing the brain of the female fetus.

We therefore have the basis of knowing how a genetic male may end up having a female brain and a genetic female a male brain, causing desynchrony between gender identity and gender role. A genetic male would have a female brain if the male fetus is exposed to compounds that inhibit conversion of Testosterone to Estrogen. These compounds are known as aromatase inhibitors. A genetic female would have a male brain if the female fetus is exposed to compounds that inhibit the formation of AFP. Environmental aromatase and AFP inhibitors can therefore cause homosexuality.

Before using another example of abnormality in sexual development to explain the biological basis of homosexuality, I cite a few studies on postnatal causes of homosexuality.

1. A family pattern of dominant or detached mothers or fathers, or cultural upbringing, in causation of homosexuality is unsupported by cross cultural or cultural affinity studies.

2. Adult levels of sex hormones in males and females can be discounted because firstly, homosexual men and women have sex hormone levels within the range of their respective sex heterosexual counterparts; secondly, high or low sex hormones tell us nothing about adult homosexuality. Finally, the adult human is not dependent on sex hormones for sexual performance. A female rat with ovaries removed and without Estrogen would not arch her back in response to male sexual advances. Male and female humans indulge in sex with equal enjoyment with or without sex hormones. Libido is not due to sex hormones, it is all in the mind of humans.

3. Homosexuality develops at an early age, at the earliest age a meaningful behavioural pattern can be discerned in children. This has circumscribed somewhat academic enquiry into homosexuality. It points to a development of homosexuality in utero i.e. in the womb. But at the same time it does not preclude homosexuality as a lifestyle option through postnatal societal influences such as rearing, learning, peer pressure and individual choice. When they do, and even choose same sex for sexual activities, they don’t necessarily refuse to have children with the opposite sex. They may have children before adopting homosexual sexual lifestyle or during the homosexual sexual lifestyle, so the pro creation evolutionary ends of sexual development is not disturbed.

A biological case for homosexuality can further be made from a special class of abnormalities of sexual differentiation. A reproductive development that enables this kind of academic enquiry is one where the development of a male’s external reproductive system aberrantly shifts toward that of the female. Such system allows us to evaluate whether, or to what extent, conflicting sexual organs in one person is reflected in conflicts in gender identity and gender role. The abnormality in sexual differentiation I use here for the purpose is testicular feminisation or androgen receptor failure or androgen insensitivity syndrome, of which I deal with the extreme form.

In this case, the genetic male (male genotype) presents as female in appearance (female phenotype). She is identified as a female because that is how she looks and appears to all when fully clothed. She has breasts and normal female pattern of fat deposition. When you take her clothes off and examine her pubic region, she has normal female body habitus and sparse pubic hair. Examination of the vagina reveals one ending in a blind pouch. In actual fact, this person is a male because he (note my change of gender) has a normal male pair of chromosomes (XY; presence of Y chromosome = male; absence of Y = female), he has two testes - both undescended and lying in the inguinal canal as small bilateral inguinal masses, and his serum testosterone levels fall within the male normal range, NOT in the female normal range.

In this case we have a male by definition of genetic sex and gonadal sex, but a female by definition of external genitalia sex and somatic sex. What then is this person’s psychic sex? What is this person’s self estimation of gender, i.e. gender identity?

These patients are seen by Medical practitioners often at puberty when they complain of lack of menstruation. They cannot menstruate because they do not have ovaries, uterus and the upper one-third of the vagina (which is why their lower two-thirds of the vagina as part of the external genitalia ends internally in a blind pouch).

In these patients it used to be routinely assumed that they had female gender identity because these genetic males had female external genitalia sex and female somatic sex, had been brought as females and had been used to the idea of being females. What was only thought required then was to reinforce their female gender identity, including hormone administration to maintain their female secondary sex characteristics. Surgery was confined to removing the undescended testes to prevent development of neoplasm, and their vagina was deepened (to reclaim the upper one third of the vagina) to make it anatomically sexually workable.

In contemporary biology, it can no longer be assumed that such persons necessarily have female gender identity by virtue of their female phenotype and rearing. After surgery to reinforce female identity, some of these persons choose to revert to a male external genitalia because they feel male i.e. have male gender identity, and say they always felt male when being reared as females in their condition. It has been found that while Estrogen masculinizes the brain, Testosterone is required to maintain the masculinization of the brain. In its absence, masculinization of the brain is reversible. It is therefore not surprising that those with complete androgen function deficiency adopt the female gender identity, and those with partial androgen function deficiency adopt the male or female gender identity. Hence, whether a person with Androgen function deficiency adopts male or female gender identity depends on the severity of the androgen deficiency. A person with partial androgen deficiency who has a male gender identity would develop serious psychiatric disturbances if made to continue with a female external genitalia and phenotype, even if that was the way he / she was reared.

The foregoing illustrates that the basis of gender identity in some homosexuals can be traced to abnormalities of sexual differentiation in utero.

I am inclined to the view that if we accept that some homosexuality is beyond a homosexual’s control, our culture and traditions would be more accommodating and we would be a touch more understanding of homosexuals. And when we are more understanding, homosexuals would not feel so besieged to advertise so blatantly their homosexuality as heterosexuals advertise theirs without the same societal restraint. I suspect the proportion of postnatal adoption of homosexual sexual lifestyles, that challenge and confront the Ghanaian cultural and traditional mind, would increase with our intolerance.